Painting wooden floorboards should be approached in much the same way as any other painting project. The floorboards should be clean and dust-free, dry and as free from pits, bumps and other irregularities as possible. Any large cracks, holes or other depressions should be repaired. Irregularities left in the floor will become glaringly visible when paint is applied. For best results, the floorboards should be free of polyurethane finishes and old, chipped or worn paint.
Sweep with a broom and mop the floorboards to remove any debris and dirt.
Sand the edges and the corners of the room. Sand outward from the corners and edges to about 15 cm. Use the orbital sander to sand the entire room, meeting the hand-sanded edges and corners. This will ensure that the entire room has been sanded.
Mop the floor with clean water two to three times to ensure all the sanding dust has been removed and the floor is clean.
Fill any large cracks, chips and other depressions in the floorboards, using wood putty and a putty knife. Wait the manufacturer-recommended time for the putty to dry; when dry, hand-sand with fine-grit sandpaper until each repaired area is smooth.
Clean the dust away thoroughly with clean, wet rags if you repaired only a few small places. Otherwise, mop the room thoroughly with clean water at least twice to ensure all the dust has been removed. Allow the floorboards to dry thoroughly. Using the wide masking tape, cover your skirting boards to protect them from the paint.
Cut-in the edges and corners of the room with primer, using your paintbrush. Paint outward from the edges and corners about 15 cm all around the room. This will allow the roller to meet these edges without touching the skirting boards and walls.
Dip your paint roller into the tray and paint the primer over the remaining surface of the room, meeting the cut-in areas. Follow the manufacturer's recommendations for drying time. Paint a second coat of primer if you like, though one is considered enough.
Apply your first coat of paint in the same manner as you applied the primer. Wait at least 24 hours before applying the second coat.
Apply a coat of clear polyurethane varnish over the paint if you want to harden the surface of the floorboards and extend durability.
Do not let anything touch or anyone walk on your painted floorboards until they are completely dry.